Providing flood hazard mapping and probabilistic flood risk assessment to support international governments.

Ambiental was commissioned by The World Bank to produce flood hazard maps and flood risk loss analysis for the state government of Santa Catarina, Brazil. Earlier this year a delegation of flood experts was sent to Brazil to deliver the results of this study and to train local government staff in how to use Ambiental’s flood data products for managing flood risk. This article provides an overview of this project’s work and our overseas visit.

The water front of Florianópolis Island, Santa Catarina state in Brazil (photo credit: Paul Drury,2016).

Land development within areas of flood hazard

Certain areas of the Santa Catarina state are extremely prone to flooding. Ambiental’s role was to produce a comprehensive flood risk assessment and catastrophic loss model to identify high risk exposure locations. The goal of this work was to inform decision makers on their risk prioritisation and mitigation strategies to achieve a better understanding of the potential flood hazard and identify ways to reduce flood risk.

Santa Catarina in Southern Brazil covers an area of almost 100,000 km2 and contains over 6 million people. The capital city Florianópolis has a wider metro area, containing São José, Palhoça and Biguaçu which are important industrial poles and commerce areas. The state contains 15 major cities. Santa Catarina state is a major industrial and agricultural centre with the corridor between Joinville, Jaraguá do Sul and Blumenau being heavily industrialised. Rapid urban expansion in recent decades has seen development in vulnerable areas where there is a high potential for devastating floods.

The rivers in Santa Catrina contribute to two main basins, the Atlantic basin and the Plata Basin. The largest rivers in these basins are the Itajaí and Uruguay-Iguazu catchments respectively. The Itajaí Basin, is home to almost 1 million people. This area has experienced frequent severe flooding, with many urban areas located within floodplains, notably the city of Itajaí which had 95% of its area affected by the 2008 floods. In November 2008 major flooding from heavy rainfall affected around 60 towns and over 1.5 million people. At least 135 people were killed, over 78,700 forced to evacuate homes, 27,400 people left homeless, 7,154 homes completely destroyed and 186,000 left without electricity for weeks. The state was flooded again in September 2011 when 6 people died and almost half a million people were affected. Recent flood events in 2013, 2014 and 2015 serve to demonstrate that flooding is becoming a serious and persistent hazard for the state.

Flooding in Santa Catarina, Brazil, 2013 (source: FloodList)

Producing flood data products for risk management

Ambiental is an established provider of deterministic and probabilistic natural hazard data. The company has experience of providing environmental risk consultancy and data solutions to a range of organisations around the world; from local and national governments through to primary and re-insurers, as well as international and intergovernmental organisations. Our project portfolio includes several previous projects with The World Bank. Ambiental is a prominent consultancy and technology provider specialising in large scale flood risk investigations and have developed skills, tools (e.g. Flowroute™) and methodologies to support catastrophic loss modelling, flood forecasting and the design of mitigation options at both strategic and implementation levels.

For this project Ambiental developed a state-wide high precision flood hazard map. This was then used within a catastrophe model. This involved the simulation of 10,000 years of realistic synthetic flooding events which were generated using a stochastic process driven by rainfall gauge data and driven by a covariance correlation matrix. This event catalogue was used to model loss estimations for an exposure portfolio which contained all of the building assets for the state. Catastrophic loss estimations were also produced for historic flooding events for the purposes of result validation and scenario based loss estimation. The product build and the bulk of the analysis work was all achieved within a tight four month development timeframe.

Ambiental’s FloodMap™ showing fluvial flood risk for Santa Catarina state.

Sending a delegation of flood risk experts to Brazil

This project included an overseas mission by Ambiental specialists to present the findings of the study, deliver the data products and share knowledge with representatives of Santa Catarina state government. Two staff were sent to the capital city of Florianópolis for a five day mission. The project findings were presented to The World Bank delegates and the Santa Catarina government during mid-April 2016. This work comprised the preparation and delivery of two presentations to explain the modelling processes and to deliver the results. In follow up a meeting was held with the Secretariat of Sustainable Development where the findings were discussed in further detail along effective strategies for communicating the findings.

The working relationship between Ambiental, the World Bank and the local consultants was very productive and ensured that the core objectives were well achieved. Happily the trip also allowed a few occasions to explore the beautiful island city of Florianopolis, and to enjoy the Brazilian sunshine and discover the local culture.

Ambiental’s Paul Drury presenting a training seminar on flood risk to Santa Catarina state government.

Delivering meaningful project outcomes

The data products generated through this work are superior to the pre-existing products available to the state government, which will enable them to leverage improvements in flood risk management more effectively. The key findings of the study will be used to inform and influence decision making in the governing of the state now and in the future. The study revealed locations where potential fluvial flood hazard is greatest and where it poses the greatest risk to life. The work quantified possible financial losses to the building stock across the entire state.

Ambiental is able to offer a variety of similar studies to customers and is actively seeking collaborations with other organisations, institutions and governments internationally. To find out more about our products and training services visit the Ambiental website and do contact us for further information. You can also follow us on Twitter and like us Facebookfor up-to-date flood news, as well as joining us on LinkedIn to receive the latest news on our products and services. We would like to thank the Santa Catarina state government, The World Bank and the local consultants for their involvement in successfully achieving the goals of this project.

The Bay of São José, from Florianópolis mainland, Santa Catarina state in Brazil (photo credit: Paul Drury, 2016).

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